Electric switch



C. E. STAHL.

ELECTRIC SWITCH.

APPLICATION FILED SEPT. 6. 1919.

1,372,207, Patented Mar. 22, 1921.;

- 07%? I "1mm UNITED STATES PATENT" OFFICE.

CHARLES E. STAHL, OF MERIDEN, CONNECTICIJ'T, ASSIGNOR TO THE CONNECTICUT TELEPHONE & ELECTRIC COMPANY, INCORPORATED, OF MERIDEN, CONNECTICUT,

A CORPORATION OF CONNECTICUT.

ELECTRIC SWITCH.

Specification of Letters Patent. Patented lVIal. 22, 1921 Application filed September 6, 1919. Serial No. 322,107.

.movement of the contact end with relation to the other contact is very slight during the ordinary operation of the system in which the switch is installed, but in which the eifective movement of the contact end is more abrupt at higher temperatures. The other contact member in the preferred form consists of an adjustable pin carried by a spring pressed plunger which is adapted to be manually reset after automatic release. The relative movement of the contact pin and the thermostatic ele ment is such that in breaking the circuit any are which may be formed is drawn across surfaces other than the surfaces which are in contact during current-carrying conditions. Furthermore, the resetting of the device cleans off the surfaces over which the arc is'drawn.

Figure 1 is a side view and partial section of a device embodying my invention, showing the parts in full lines intheir currentcarrying or closed-circuit relation and indicating in dotted lines the position of the contact members when the circuit is opened.

Fig. 2 is an edge view of the same. Fig. 3 is a bottom plan view. In this particular-form the base 5, is of insulating material in which is molded the tubular post 6 with whichone of the circuit wires-may be connected by a binding screw 7. In this post is mounted a plunger 8 which is, pressed upward. by aspring 9.v

From this plun r extends a contact pin 10 which is prefe rably adjustable through the plunger. This pin is adapted; to travel in the slot 11' of thepost 6.-"The': 'plunger is preferably provided with 'a button 12 at its outer and for pushing the plunger in.

The thermostatic element 13 may be formed of suitable material adapted to be bent or warped by heat. The lower end of this is bent .to .form a foot 14 which is seated in a recess in the base 5 and the outer end is bent into a hook-like form at 15 to engage the contact pin 10. The foot may be secured in position b a stud '16 which however is insulated rom it by a washer 17. A binding screw '18 co-acts with the stud 16 at one end and a resistance strip or wire 19 is electrically connected to the other end 20. This strip 19 is wound around the main arm of the thermostatic member, being insulated therefrom by a layer of insulating material 21 throughout most of its length and electricall connected at 22.

'In the position shown in full lines in the drawing the circuit extends fromthe binding screw 7 through the tubular post 6, plunger 8, contact pin 10, contact tip 15, the upper end of the arm 13, coiled strip 19 and the stud 16 to the binding screw '18.

As current flows through the switch, the

coil 19 heats up the thermostatic arm 13 andcauses its upper end to move away from the post 6. At the same time the contact tip 15, moves toward the post although to a somewhat less extent due tov the fact that the tip is shorter and the heat is more concentrated in that part of the arm which is surrounded by the coil 19. The parts are so proportioned that at the higher temperatures the radiation from the contact tip 15 is so rapid that the end moves but little relatively to the main body of the thermostatic element (the radiation of course bein more rapid at higher temperatures). t the higher temperatures therefore, the movement of the contact tip 15 toward the right is substantially identical with the movement of the main arm- 13 and consequently the contact tip is moved quickly away from the contact pin 10 at the time when it is desired that the circuit shall open automatically.

In the circuit-opening movement any are- Which is formed will be drawn across the outer end of the contact pin 10 and along staticelement The resetting of the switch .the'inclined face 23 oftl'ie tipof the thermobase, a tubular post carried thereby, a

spring pressed plun'ger operable in said post, a pin projecting from said plunger, a thermostatic element having a main arm mounted alongside of said postand having its tip end engaging the outer face of said pin.

2. In an electric-switch, a longitudinally movable member having a transversely extending contact pin, a thermostatic element mounted alongside of said member and having its tip end engaging the outer surface of said pm, the outer wall of said thermostatic element being inclined relative to the direction of movement of said pin.

3. In an electric switch, an insulating base, a tubular post carried thereby, aplunger movable in said post, an adjustable con tact member carried by said plunger and a thermostatic arm secured to said base and having a reversely extending end engaging said contact member.

4. In an electric switch, an insulating base, a tubular post carriedthereby, a spring pressed plunger reciprocable in said post, a transversely adjustable contact member carried by said post, said plunger being adapted to be set by hand, a thermostatic element secured to said base and havin a reversely extending contact tip engaging t e outer face of said adjustable contact member, and a resistance coil for heating a part of said thermostatic element.

5. In an electric switch, a spring pressed reciprocable contact, a thermostatic arm arranged adjacent thereto and having a reversely extending contact tip normally engaging said contact, and means for heating a part of said thermostatic element whereby a differential action of the contact tip with respect to the remainder of the ther-' mostatic arm is efiected at certain temperatures and the contact tip moves at substantially the same rate as the remainder of the thermostatic arm at higher temperatures.

6. In an electric switch, a spring pressed contact member, a thermostatic arm having its free end extending in the opposite direction to the main portion thereof and adapted to engage said contact member to conduct current therethrough under normal conditions, and means for heating the main portion of said arm so as to moveit away from said contact and at the same time move its end toward said contact to avoid breaking the circuit over a certain range of temperatures, the proportions of the parts of said arm and its end being such that its end moves with the main part at temperatures above a predetermined value.

7. In an electric switch, a spring pressed member having a shoulder, a thermostatic arm having its free end extending in the opposite direction to the main portion of said arm and normally engaging said shoulder, and a coil surrounding only a portion of said arm whereby the thermostatic movement of the free end of said armover a certain range of temperatures is in a direction opposite to the movement of the main portion of said arm, so as, during said range, to retain engagement with said shoulder, and whereby radiation from the end of said arm at higher temperatures causes a differential movement between the mainportion and the end of said arm so as to cause the end of said arm to be disengaged from said shoulder.

8. In an electric switch, a spring pressed member having a shoulder, means for manually moving said member and shoulder against the pressure of said spring, a therinostatic arm arranged alongside of said spring pressed member and having its free end extending in the opposite direction to the main portion of said arm and adapted to engage said shoulder, and a heating coil surroundin a portion of the main arm only, where y there is permitted a differential thermostatic action between the main portion of said arm and the end thereof.

' CHARLES E. STAHL. 

